Update: Matt Cutts told me this is a fairly major update to the Panda algorithm affecting 2.4% of search queries. More on this over here.

The number of complaints and comments about this update is pretty up there. The levels of concern and those reporting ranking declines is huge. So it seems to have hit the SEO industry pretty hard. As hard as Panda or Penguin? Doubt it but time will tell.

That being said, to make things even more confusing, @GregrySmith was able to get Google's Matt Cutts to confirm that the EMD update was not the only update happening at that time. Matt confirmed on Twitter that at least one other update was released around the same time.

What exactly did that "other" update impact? Smith asked "As an Authority Local SEO Company all sites we reviewed that was hit by EMD update was not EMD's at all.Can you explain this?" Matt Cutts responded, "yes. 500+ algo launches/year mean 1-2 a day. I know of at least one other algo rolling out over same timeframe for example."

Here is the embed:

@gregrysmith yes. 500+ algo launches/year mean 1-2 a day. I know of at least one other algo rolling out over same timeframe for example.